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ZnO/La2O3 mixed oxides are prepared by a coprecipitation method at different molar ratios and used as catalysts for the synthesis of glycerol carbonate by transesterification of glycerol with dimethyl carbonate (DMC). X-ray diffraction, N2 adsorption, transmission electron microscopy, scanning electron microscopy, and thermal-programmed desorption methods were used for characterization of the catalysts. The surface area and porosity of the catalysts prepared by the precipitation method proved to be better than those prepared by combustion and modified-citrate methods. Zn4La1 and Zn2La1 (mole ratio Zn:La of 4:1 and 2:1, respectively) were found to be the best proportions in view of both higher activity and higher selectivity. The rates offered by these catalysts were substantially high compared to reported Mg/La and other catalysts. The effects of parameters such as the temperature, catalyst loading, and mole ratio of DMC to glycerol were examined, and a suitable kinetic model was proposed for the Zn4La1 catalyst.

Propylene glycol methyl ether acetate is an industrially important solvent. In this work, we study the applicability of reactive distillation (RD) for its synthesis in the presence of an ion-exchange resin, Amberlyst 15, as a catalyst. Simultaneous separation of water during the course of reaction shifts the reaction in the forward direction, which renders cost effectiveness and compactness to the process. The presence of an azeotrope between methoxy propanol and water complicates the separation, leading to a loss of reactants in the product streams, thereby hampering both conversion and purity. Toluene is thus used as an entrainer to further intensify the process. In this work, the intrinsic kinetic parameters are determined from batch reactor data, and used subsequently to simulate the column performance. An experimentally validated simulator is used to examine the effect of various operating and design parameters. Reactant and product losses are minimized to negligible levels and a significant increase in the conversion is realized.

The integration of chemical reaction and chromatographic separation in a single unit is known as reactive chromatography (RC). RC may be beneficial for processes that involve mixtures, which are otherwise difficult to separate by conventional distillation due to nonideality in the phase equilibrium, formation of azeotropes, etc. In this work, synthesis of n-propyl acetate from n-propanol and acetic acid using Amberlyst-15 as a catalyst/adsorbent in a fixed bed chromatographic reactor (FBCR) is investigated. The parameters in the rate model, adsorption isotherm, and dispersion model are estimated using experimental data. The reactive separation experiments are performed in a FBCR setup and the results are compared with model predictions. The breakthrough profiles of FBCR indicate that the synthesis of n-propyl acetate using RC may be advantageous compared to conventional reactors.

Reactive chromatography (RC) is a promising technology, wherein equilibrium limitations are overcome by simultaneous reaction and adsorptive separation in a single unit. This operation, on a large scale, can be performed conveniently in a simulated moving bed reactor (SMBR) in continuous mode. In this work, we demonstrate the use of an SMBR for the synthesis of 2-ethylhexyl acetate through experiments and simulations. The kinetic model and Langmuir adsorption isotherm, which serve as inputs to the simulator, were taken from an earlier study Mahajani Sep. Sci. Technol. 2008, 43, 2245). A parametric study was performed using the experimentally validated simulator by varying one of the parameters at a time, to yield desired performance in terms of conversion, purity, productivity, and desorbent consumption. The trends in the results are explained with the help of variations in the solid and liquid concentrations. The simulation results indicate that an SMBR unit containing eight columns is able to offer almost quantitative conversion and purity with a typical desorbent requirement of 46.35 mol of acetic acid per mole of product and a productivity of 32.01 mol of product per kilogram of adsorbent per day. Further optimization of the performance and application of a systematic design algorithm are developed and presented in part II of this work.

A simulated moving bed reactor (SMBR) is a multifunctional reactor wherein the reaction and chromatographic separation take place simultaneously. The positions of the inlet and outlet ports are switched at periodic intervals to simulate a true moving bed system. The design exercise for these units is a challenging task due to the large number of degrees of freedom such as the column volume, SMBR configuration (i.e., number of beds in each section), sectional flow rates, switch time, desorbent concentration and feed concentration. In this work, we propose a simulation based design methodology for the SMBR process that is employed for heterogeneously catalyzed reversible reactions, in which one of the reactants works as a solvent and the catalyst also plays the role of adsorbent. The objectives are productivity (PR) maximization and desorbent consumption (DC) minimization which have a direct impact on the total annualized cost of the process. The performance parameters such as conversion, raffinate purity, and extract purity are chosen as constraints. The model reaction considered is the esterification of acetic acid with 2-ethylhexanol catalyzed by cation exchange resin.

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